Serializer Registration

[scrogson]

This PR changes the way serializers are registered. It removes the need for serializers to be added to the :oauth2 application config.

Instead, serializers are now registered in code with OAuth2.Client.put_serializer/3. This allows wrapper libraries to provide custom serializers without users needing to be concerned with configuring the :oauth2 application.

/cc @tsubery (#88)

[coveralls]

Coverage decreased (-0.8%) to 94.231% when pulling 88761bb on register_serializers into 6d1808c on master.

[snewcomer]

@scrogson Recently came across a good use case here: ueberauth/ueberauth#87.

If you don't have time, I would be happy to pick up the flag on this one. Otherwise, I can review if you are still interested in merging this PR!

[scrogson]

Hey @snewcomer,

I've got a new design that I want to work on that will remove the need for a centralized configuration and rely on the configuration to be on the OAuth2.Client struct itself. This will allow for greater flexibility and power.

[snewcomer]

This is looking great @scrogson. Lmk if you need an 👁yet!

[scrogson]

@snewcomer @doomspork I'd love some eyes on this! ❤️

[doomspork]

@scrogson Happy Holidays homie! I will take a peek this weekend and get back to you. Hope all is well with your family 😁

[doomspork]

Looking good @scrogson! I have only 1 real question and it's the purpose of OAuth2.Serializer.Null. This seems so different from how most Elixir libraries work, I'm not sure it's a win or potential source for confusion. I think you could pull maybe_warn_missing_serializer function out and do away with a serializer that doesn't really serialize.

[snewcomer]

Looks great! Not much for me to comment on :)

How does this look (references this PR)? ueberauth/ueberauth_google#58

[scrogson]

How does this look (references this PR)? ueberauth/ueberauth_google#58

@snewcomer hey, sorry for the delay. That PR looks like it will be perfect once this lands. Thanks for that.

I need to clean up a few things and I'll try to get it merged and a new version published.

[scrogson]

@doomspork calling for one last review....

[snewcomer]

🙇

[doomspork]

Looks good @scrogson 👍

[adamniedzielski]

@scrogson was it an intentional decision that this PR changes version requirement for hackney from ~> 1.7 to ~> 1.13.0? This is a more restrictive requirement, because ~> 1.7 allows for example 1.15.1, but ~> 1.13.0 no.

I was trying to update oauth2 from 0.9.4 to 1.0.0 and this required a downgrade of hackney (along with some transitive dependencies coming from hackney). At the same time, there's no discussion in this PR related to changing hackney version requirement, so I was thinking that I'd better double-check with you. I can also open a new issue if you prefer 😄